This invention relates generally to improved means for machining various solid materials with assistance of a high velocity fluid jet stream including the method therefor, and more particularly to a modified cutting insert which enables improved cutting action.
Material cutting operations such as turning, milling, boring, shaping and grooving conventionally employ working fluids for cooling and lubrication. These fluids are generally liquids such as water and other liquid dispersions which are dispensed in various ways at the tool interface with material being removed when a particular cutting operation is being carried out. High velocity jet streams are now being utilized to improve the lubrication and cooling mechanisms involved for reduced machining costs and extended tool life particularly with respect to metal machining which typically utilizes various type metal cutting inserts. For example, there is disclosed in U.S. Pat. No. 4,621,547 a method and means being employed with a turning lathe which includes a metal cutting insert provided with external coolant delivery means to discharge a high velocity jet of the coolant which flows across the top surface of the insert toward the cutting edge-workpiece interface. As therein described, the high velocity jet of coolant is ejected between the top surface of the cutting insert and underside of the chip from a discharge orifice in the tool holder. The coolant flows through an internal passageway provided in the tool holder by a delivery line connected at one end to the clamping member of the tool holder and at the other end to a pump with rating of about 1000-3000 PSI. The coolant is conveyed within the clamping member by a connector passageway connected at one end with the delivery line and communicating with the entrance opening of such internal transition passageway. Tool feed rate, orifice distance and coolant velocity are further reported to be critical in obtaining improved chip control and tool life with the disclosed apparatus. Similar apparatus means for machining a metal workpiece are also disclosed in U.S. Pat. No. 4,695,208 wherein the tool holder generally comprises a support bar formed with a cavity which is adapted to receive a shim in the form of flat plate or support block formed with a seat. An insert having a top surface terminating with a cutting edge is mounted atop the shim or within the seat in the support block so that the top surface of the insert is exposed and the cutting edge extends outwardly from the holder. Again, coolant delivery means physically separate from the cutting insert are provided in the tool holder which delivers a high velocity coolant jet across the exposed top surface of the insert toward its cutting edge and beneath the underside of chips formed from a workpiece. Such manner of coolant delivery is reported to achieve improved chip breakage and increased tool life but is further said to require structural means to guide the chip into substantial alignment with the cooling jet in order to do so.
Jet cooling assistance for metal machining at higher delivery pressures is also disclosed in a technical article entitled "Metal Machining with High Pressure Water--Jet Cooling Assistance--A New Possibility" authored by M. Mazurkiewicz, Z. Kubala and J. Chow, Journal of Engineering for Industry, Volume 111/7 (February 1989). As disclosed therein, external jet orifice means provide the coolant jet which is directed at the intersection between the cutting edge of a metal cutting insert and the metal chip being formed utilizing an otherwise conventional turning lathe apparatus. The physically separate and distinct jet orifice means being utilized therein is reported to feature nozzle diameters in the range 0.135-0.35 millimeters with fluid velocities being reported to reside in the range from 370-740 meters per second. The pressurized water being delivered to the cutting area by such means is said to be supplied with high pressure tubing connected to the jet nozzle. At the defined metal cutting conditions, significant improvement is reported for both material removal rate and desired short chip formation even with poorly machinable metals.
It is one object of the present invention to provide still more effective means to conduct fluid jet assisted machining of various solid materials.
Another important object of the present invention is to provide a novel method for conducting fluid jet assisted machining of various solid materials.
Still a further object of the invention is to provide a novel metal cutting insert enabling discharge of a high velocity fluid stream therefrom in an improved manner.
Another object of the invention is to provide a novel tool holder for improved jet assisted machining of a metal workpiece.
These and still further objects of the present invention will become apparent upon considering the following detailed description of the present invention.